It was Good Friday evening when vet Charlie got the call. The Hall family had been out all afternoon at a local event and had returned home to find the children’s hidden Easter eggs had been raided by their two dogs: 10yo Yorkie Millie and 2yo Labrador Smudge. The dog-walker had been in to see them around 3pm and not noticed anything amiss. However the mischief had been done upstairs where she hadn’t been. The chocolate could therefore have been eaten anytime between around 1pm and 7pm when Mrs Hall had discovered the open wardrobe and strewn packaging.
On the phone, Mrs Hall said she thought Smudge was the likely troublemaker, but she couldn’t be sure which dog had eaten what. Smudge seemed fine but Millie was acting a little oddly and there was a couple of piles of vomit in the kitchen. Vet Charlie advised to bring both dogs in straight away and bring the remaining packaging with them.
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Chocolate toxicity in dogs
Chocolate is one of the most common toxicities in dogs, according to the Veterinary Poisons Information Service (VPIS). It contains a substance called theobromine, which is harmless to humans but toxic to dogs. The caffeine in chocolate is also bad for pets. The severity of the toxic effect will vary depending on the type of chocolate eaten, the amount eaten and the size of the dog. The amount of theobromine in chocolate varies a lot. Generally, the darker the chocolate, the higher the concentration of theobromine. So dark chocolate is toxic in smaller amounts than milk, although both can be poisonous in the right amounts. Cocoa powder is very toxic due to its high concentration of theobromine. White chocolate doesn’t contain any cocoa solids, so isn’t poisonous. Although the high fat content can still cause an upset tummy.
Mrs Hall arrived at the veterinary surgery 10 minutes later with both Millie and Smudge and was taken straight in by Dr Charlie. After examination, Charlie was very concerned. Smudge was perfectly normal on clinical exam and was showing no signs of toxicity. But Millie was agitated, had a high heart rate, and she also was sick whilst in the consulting room.
Symptoms of chocolate toxicity
Theobromine toxicity affects the gastrointestinal system, nervous system and heart. Signs usually appear within 2-4 hours after ingestion, but can be seen up to 12 hours. Typical symptoms include vomiting and diarrhoea, restlessness and agitation, increased thirst and urination, panting and tummy (abdominal) pain. This can progress onto more severe signs such as shaking and tremors, fever, increased heart and breathing rates, high blood pressure, seizures, muscle rigidity and coma.
After examining the remaining packaging, the vet was very concerned that the dogs may have eaten enough chocolate to cause severe toxicity. The eggs had been a mix of dark and milk chocolate and there were multiple eggs missing. Smudge the Labrador weighed 25kg, but Millie was a tiny Yorkie who only weighed 3.5kg. VPIS recommend treatment for ingestion of dark chocolate amounts over 3.5g/kg and milk chocolate over 14g/kg, and list the toxic dose at 20mg/kg, with severe signs over 45-50mg/kg. Smudge would have to have eaten a lot of chocolate to be at serious risk, but Millie’s toxic dose was much lower – and she was already showing some symptoms.
But who ate which eggs?
As it was unsure when the dogs had eaten the chocolate, Vet Charlie gave Smudge an injection to make her vomit, to try and limit the damage by removing any undigested chocolate from the stomach. Millie was already being sick, and with a high heart rate and blood pressure, she required further and urgent treatment. Smudge responded well to the emetic (sickness) injection and brought up some small pools of chocolatey vomit.
The vet explained that Millie was more of a concern than Smudge, because she was so much smaller and therefore the same amount of chocolate would have a far greater effect on her. She was also showing physical signs of toxicity. She needed treatment to control her symptoms and to try and flush the toxins out. However, as they didn’t know when the chocolate had been eaten, Smudge was still potentially at risk as she may have absorbed some chocolate before they managed to make her sick. She wasn’t showing any signs of toxicity, and her toxic dose was much higher, so she could either go home for careful monitoring, or the absolute safest option was to keep her in at the hospital for some fluid therapy and toxin-binding medicine.
Treatment for chocolate toxicity
If your dog has eaten chocolate within the last few hours, your vet will likely give them any injection to make them sick. Common further treatment involves activated charcoal; a substance given by mouth which helps to bind any toxins in the gut and pass them safely through. Your dog may also need to be put on an intravenous fluid drip, to support organ function. Severe symptoms such as seizures may need further medication, such as anti-seizure drugs or even sedation. Dogs will need close monitoring post chocolate ingestion, either at home or at the vets.
The vet gave an estimate for treatment costs
Veterinary emergency care can be expensive, especially over a Bank Holiday weekend, and with urgent and intensive care required for Millie. Luckily, both dogs were insured so Mrs Hall opted for both dogs to stay at the hospital.
Smudge was given some activated charcoal, placed on an intravenous drip and carefully monitored. She didn’t develop any symptoms of toxicity and was discharged home the next morning. The insurance company covered all costs for both dogs, minus the owners’ excess.
Millie was placed on a drip and given repeated bouts of activated charcoal. She had multiple bouts of sickness and diarrhoea, and she spiked a high temperature. When she showed signs of some muscle rigidity and tremors the vet immediately started her on anti-seizure medication. Unfortunately, Millie didn’t respond to treatment. She rapidly developed severe seizures and was placed under sedation in an attempt to control this. Her heart rate and blood pressure increased further, and she developed a cardiac arrhythmia. Despite intensive care overnight, Millie sadly passed away on Easter Saturday.
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Prognosis
Thankfully, Millie is a rare case, and most cases of chocolate toxicity are more similar to Smudge’s story. Chocolate poisoning is common, but rarely fatal. Out of 1000 recorded cases by VPIS, only 5 were fatal. Many dogs will make a full recovery with prompt treatment. Sadly, Millie’s small size and large amount of chocolate ingested lead to an extremely severe toxic dose of theobromine, whereas the larger and younger Smudge survived.
Always keep chocolate and cocoa powder well away from pets, and be especially cautious around festive periods such as Christmas and Easter.
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